Intercomparison of coral oxygen isotope data and historical SST: Potential for coral-based SST eld reconstructions
نویسندگان
چکیده
We examine the extent to which the large-scale features of the sea surface temperature (SST) anomaly eld are resolved by a sparse observational network of coral oxygen isotope ( 18O) time series. Regression of annually-averaged 18O data against gridded estimates of local SST anomaly within the period 1856{1990 con rm the literature regression of 18Oanomaly on SST anomaly for Indo-Paci c corals. But while interannual SST variability is generally well-represented by individual coral time series, observed decadal and secular variability does not always display a linear relationship to local SST anomaly. Instead, many records appear to better recover non-local, large-scale phenomena, which in turn is related to either the coral-local SST, or SST-covariant changes in sea water 18O. We employ empirical orthogonal function (EOF) analysis to see if the coral data share common patterns of variability. We nd two signi cant (and one near-signi cant) patterns of variability. The rst two patterns are interpretable as the oceanographic signature of the El Ni~ no-Southern Oscillation (ENSO), and as a near-global warming in which the eastern equatorial Paci c cools. A third pattern weakly resembles the Paci c Decadal Oscillation. These modes are seen more clearly in a singular vector decomposition (SVD) of the covariance between the coral data and the dominant patterns of large-scale historical SST variability. The results are consistent with those found in EOF and SVD analyses of historical analyzed SST data from the coral locations. As additional coral-based proxy estimates of SST become available, they will improve the resolution of the patterns recovered. These results suggest that a sparse network of coral data may be used to reconstruct interannual, secular, and decadal SST variability for pre-instrumental periods, albeit with large uncertainty.
منابع مشابه
Intercomparison of coral oxygen isotope data and historical sea surface temperature (SST): Potential for coral-based SST field reconstructions
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